Nanometer enhanced polyformaldehyde composite plastic particle and preparation method thereof

Abstract

The invention discloses a nano-reinforced polyformaldehyde composite plastic particle and a preparation method thereof. The nano-reinforced polyformaldehyde composite plastic particle comprises the following raw material components in percentage by mass: 52.4-82.4% of a copolyformaldehyde matrix; 5.4%-25.4% of a nano reinforced phase; an electromagnetic shielding phase: 8.1%-11.9%; 3.1%-4.9% of a self-repairing phase; 0.2%-0.5% of a recovery auxiliary agent; 0.2%-0.5% of a coupling agent; the invention relates to the technical field of composite materials. According to the nano-enhanced polyformaldehyde composite plastic particle and the preparation method thereof, interface optimization and multi-scale enhancement are performed on a polyformaldehyde matrix through the carbon nanofibers, the boron nitride nanosheets and the graphene, agglomeration is not prone to occurring, and the tensile strength, the heat conductivity and the fracture toughness are improved; the contradiction between processing and self-repairing performance is solved through a siloxane repairing agent coated with polymethyl methacrylate and poly (N-isopropylacrylamide), the shielding bandwidth is improved through cooperation of multi-walled carbon nanotubes and ferroferric oxide nanoparticles, ultraviolet light degradation of the material is achieved through cooperation of a nano benzophenone photodegradation initiator, and the self-repairing performance of the material is improved. The recovery efficiency is improved and the recovery cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and specifically to a nano-enhanced polyoxymethylene composite plastic particle and a preparation method thereof. Background Art

[0002] Polyoxymethylene (POM), also known as acetal resin and polyoxymethylene, is a thermoplastic crystalline polymer, known as "super steel" or "acetal steel". It is a polymer obtained by polymerizing formaldehyde, with a low degree of polymerization and easy to depolymerize by heat. As an engineering plastic with excellent mechanical strength and dimensional stability, polyoxymethylene is widely used in the fields of automobiles, electronics, machinery, etc.

[0003] In order to improve the performance of polyoxymethylene, adding carbon nanofibers can increase the tensile strength of polyoxymethylene to more than 100 MPa, but the dispersibility is poor; adding boron nitride nanosheets can improve the thermal conductivity of polyoxymethylene, but the interfacial bonding is weak; adding a self-healing coating using epoxy resin microcapsules has insufficient heat resistance and cannot adapt to the processing temperature of polyoxymethylene at 160°C - 180°C; filling polyoxymethylene with single-walled carbon nanotubes can achieve electromagnetic shielding, but the shielding bandwidth is narrow, and usually the solvent method is used for recycling, with high recycling costs and low efficiency.

[0004] Based on the retrieval of the above information, it can be seen that traditional polyoxymethylene composite materials have the following defects: I) Single function: It is difficult to meet the requirements of electromagnetic shielding and self-healing scenarios; II) Contradiction between processing and performance: Nano-enhanced materials are prone to agglomeration, and self-healing coatings are prone to failure during processing; III) Difficult recycling: Traditional pyrolysis recycling has high energy consumption, large pollution, and low recovery rate.

[0005] In view of this, a nano-enhanced polyoxymethylene composite plastic particle and a preparation method thereof are specifically proposed. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides a nano-enhanced polyoxymethylene composite plastic particle and a preparation method thereof, which solve the problems that traditional polyoxymethylene composite materials are difficult to meet the requirements of electromagnetic shielding and self-healing scenarios and are difficult to recycle.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: A nano-enhanced polyoxymethylene composite plastic particle, the raw material components of which include, by mass percentage: Copolyoxymethylene matrix: 52.4% - 82.4%; Nano-enhanced phase: 5.4% - 25.4%; Electromagnetic shielding phase: 8.1% - 11.9%; Self-healing phase: 3.1% - 4.9%; Recycling aid: 0.2% - 0.5%; Coupling agent: 0.2% - 0.5%.

[0008] The present invention is further configured such that: the polyoxymethylene matrix includes trioxane and dioxolane, wherein the mass ratio of trioxane to dioxolane is: 19 - 21:1 - 3.

[0009] The present invention is further configured such that: the nano-enhanced phase includes carbon nanofibers, boron nitride nanosheets, and graphene, and the carbon nanofibers, boron nitride nanosheets, and graphene are in a weight ratio of: 0.5 - 1:2 - 3:1 - 2; The length of the carbon nanofibers is 5 - 10 μm; The sheet diameter of the boron nitride nanosheets is 100 - 500 nm; The specific surface area of the graphene is 500 - 600 m 2 / g.

[0010] The present invention is further configured such that: the electromagnetic shielding phase includes multi-walled carbon nanotubes and iron oxide nanoparticles, and the mass ratio of the carbon nanotubes to the iron oxide nanoparticles is: 5 - 8:2 - 4; The diameter of the carbon nanotubes is 10 - 20 nm; The particle size of the iron oxide nanoparticles is 5 - 8 nm.

[0011] The present invention is further configured such that: the self-healing phase includes a silicone repair agent coated with polymethyl methacrylate and poly(N-isopropylacrylamide), and the mass ratio of polymethyl methacrylate, poly(N-isopropylacrylamide), and the silicone repair agent is: 6 - 8:2 - 4:14 - 17; The silicone repair agent contains 3% - 5% of a sterically hindered phenol heat stabilizer.

[0012] The present invention is further configured such that: the recycling aid is a nano-benzophenone photo-degradation initiator, and the particle size of the nano-benzophenone photo-degradation initiator is 10 - 30 nm.

[0013] The present invention is further configured such that: the coupling agent is a KH-500 coupling agent.

[0014] The present invention provides a nano-enhanced polyoxymethylene composite plastic particle and a preparation method thereof. It has the following beneficial effects: The present invention optimizes the interface and enhances in multiple scales for the polyoxymethylene matrix through carbon nanofibers, boron nitride nanosheets and graphene, which are not easy to agglomerate, and improves the tensile strength, thermal conductivity and fracture toughness. Through the silicone repair agent coated with polymethyl methacrylate and poly-N-isopropylacrylamide, the thermal damage of the self-healing phase during the processing can be avoided, and the contradiction between the processing and self-healing properties can be solved. Through the cooperation of multi-walled carbon nanotubes and iron oxide nanoparticles, the shielding bandwidth is improved. With the setting of the nano-benzophenone photocatalytic degradation initiator, the ultraviolet degradation of the material is realized, the recycling efficiency is improved, and the recycling cost is reduced. Detailed implementation mode

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0016] Example 1 A kind of nano-enhanced polyoxymethylene composite plastic particle, and the raw material components are in mass percentage as follows: polyoxymethylene matrix: 52.4%, nano-enhanced phase: 25.4%, electromagnetic shielding phase: 8.1%, self-healing phase: 3.1%, recycling aid: 0.5%, KH-500 coupling agent: 0.5%, wherein the recycling aid is nano-benzophenone photocatalytic degradation initiator, and the particle size of the nano-benzophenone photocatalytic degradation initiator is 10 nm.

[0017] As a detailed description, the polyoxymethylene matrix includes trioxymethylene and dioxolane, and the mass ratio of trioxymethylene to dioxolane is: 19:3; the processing method of the polyoxymethylene matrix includes: Adding trioxymethylene and dioxolane into a reaction kettle, adding 0.1 wt% of BF3 catalyst, polymerizing at 70 °C for 4 h to generate a polyoxymethylene prepolymer, then adding triethylamine with a molar ratio of 0.75 to neutralize the unreacted BF3 catalyst, and obtaining the polyoxymethylene matrix after drying.

[0018] In order to achieve the multi-scale enhancement of tensile strength, thermal conductivity and fracture toughness, and solve the problem of easy agglomeration, the nano-enhanced phase includes carbon nanofibers, boron nitride nanosheets and graphene, wherein the length of the carbon nanofibers is 5 μm, the sheet diameter of the boron nitride nanosheets is 100 nm, the specific surface area of graphene is 500 m 2 / g, and the weight ratio of carbon nanofibers, boron nitride nanosheets and graphene is: 0.5:2:1.

[0019] To improve the shielding bandwidth and provide the advantage of magnetic separation during material recycling, the electromagnetic shielding phase includes multi-walled carbon nanotubes and magnetite nanoparticles. Among them, the diameter of the carbon nanotubes is 20 nm, the particle size of the magnetite nanoparticles is 8 nm, and the mass ratio of the multi-walled carbon nanotubes to the magnetite nanoparticles is 8:4. The processing method of this electromagnetic shielding phase includes: Add multi-walled carbon nanotubes to a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, reflux at 80 °C for 6 h to introduce carboxyl groups and improve dispersibility. Then, centrifuge and wash with deionized water until the pH > 5, and obtain oxidized multi-walled carbon nanotubes after drying. Disperse the oxidized multi-walled carbon nanotubes in ethanol with a concentration of 1 mg / mL, add magnetite nanoparticles, ultrasonic for 30 min, and then let it stand for 12 h. Then, under argon protection, heat-treat at 200 °C for 1 h to obtain the electromagnetic shielding phase. Disperse the electromagnetic shielding phase in ethanol with a concentration of 1 mg / mL, and disperse it with a high-speed shear machine at 3000 rpm for 10 min to obtain a stable suspension.

[0020] To solve the contradiction between the processing and performance of the self-healing coating, the self-healing phase includes a silicone repair agent coated with polymethyl methacrylate and poly(N-isopropylacrylamide). The silicone repair agent contains 5% sterically hindered phenol heat stabilizer, and the mass ratio of polymethyl methacrylate, poly(N-isopropylacrylamide) to the silicone repair agent is 6:2:17. The processing method of this self-healing phase includes: Mix methyl methacrylate with a 1 wt% BPO initiator, add it to a microfluidic chip with a channel width of 100 μm, with a flow rate of 5 μL / min, and initiate polymerization under ultraviolet light with an intensity of 10 mW / cm² at 70 °C to generate a PMMA prepolymer. Dissolve N-isopropylacrylamide and a 2 wt% BIS cross-linking agent in dimethylformamide, inject it into a microfluidic channel with a channel width of 100 μm, with a flow rate of 3 μL / min, and react at 40 °C for 15 min to obtain a PNIPAM prepolymer. 2 Load the PMMA prepolymer and the PNIPAM prepolymer into the outer layer and the inner layer of a coaxial syringe respectively, and spray them into a rotating collector rotating at 2000 rpm under a 15 kV high-voltage electric field to obtain microcapsules. Irradiate the microcapsules with ultraviolet light at 365 nm for 10 min, with an intensity of 50 mW / cm², to form microcapsules with a PMMA / PNIPAM interpenetrating network. Heat the silicone repair agent containing 5% sterically hindered phenol curing agent to 80 °C, and infiltrate it into the pores of the microcapsules through capillary action in a -100 kPa vacuum device. Then, keep it at 80 °C for 2 h to allow partial cross-linking of the silicone with the inner layer PNIPAM of the shell material to obtain the self-healing phase. Load the PMMA prepolymer and the PNIPAM prepolymer into the outer layer and the inner layer of a coaxial syringe respectively, and spray them into a rotating collector rotating at 2000 rpm under a 15 kV high-voltage electric field to obtain microcapsules. Irradiate the microcapsules with ultraviolet light at 365 nm for 10 min, with an intensity of 50 mW / cm², to form microcapsules with a PMMA / PNIPAM interpenetrating network. Heat the silicone repair agent containing 5% sterically hindered phenol curing agent to 80 °C, and infiltrate it into the pores of the microcapsules through capillary action in a -100 kPa vacuum device. Then, keep it at 80 °C for 2 h to allow partial cross-linking of the silicone with the inner layer PNIPAM of the shell material to obtain the self-healing phase. 2 Heat the silicone repair agent containing 5% sterically hindered phenol curing agent to 80 °C, and infiltrate it into the pores of the microcapsules through capillary action in a -100 kPa vacuum device. Then, keep it at 80 °C for 2 h to allow partial cross-linking of the silicone with the inner layer PNIPAM of the shell material to obtain the self-healing phase.

[0021] Example 2 This example is applied to a nano-enhanced polyoxymethylene composite plastic particle provided in Example 1, and its preparation method specifically includes the following steps: S1. Add the copolymerized polyoxymethylene matrix and the nano-enhanced phase to a high-speed mixer, premix at 1500 rpm for 5 min, and perform melt plasticization using a twin-screw extruder. The feeding section is at 140 °C, the melting section is at 160 °C, and complete melt plasticization within 30 s at 800 rpm. During the process, add the electromagnetic shielding phase to the melting section of the twin-screw extruder through a side feeding port, and then pelletize the extrudate to obtain semi-finished composite particles; S2. When the semi-finished composite particles are cooled to 60 °C, spray the self-healing phase dispersed in ethanol on the surface of the semi-finished composite particles through an electrostatic spraying device to obtain enhanced composite particles; S3. Place the enhanced composite particles in a plasma treatment device, pass argon at 60 sccm, treat at a power of 300 W for 2 min, then spray an ethanol solution containing 0.5 wt% coupling agent, and dry in an 80 °C environment for 1.5 h to obtain nano-enhanced polyoxymethylene composite particles.

[0022] Example 3 The difference between this example and Example 1 is as follows: For a nano-enhanced polyoxymethylene composite plastic particle, the raw material components are by mass percentage: copolymerized polyoxymethylene matrix: 67.4%, nano-enhanced phase: 15.4%, electromagnetic shielding phase: 11.9%, self-healing phase: 4.9%, recycling aid: 0.2%, KH-500 coupling agent: 0.2%, where the recycling aid is a nano-benzophenone photo-degradation initiator, and the particle size of the nano-benzophenone photo-degradation initiator is 20 nm.

[0023] The mass ratio of trioxymethylene to dioxolane is: 20:2.

[0024] The length of the carbon nanofibers is 8 μm, the sheet diameter of the boron nitride nanosheets is 300 nm, the specific surface area of the graphene is 550 m 2 / g, and the weight ratio of the carbon nanofibers, boron nitride nanosheets and graphene is: 0.8:2.5:1.5.

[0025] The diameter of the carbon nanotubes is 15 nm, the particle size of the iron oxide nanoparticles is 7 nm, and the mass ratio of the carbon nanotubes to the iron oxide nanoparticles is: 7:3.

[0026] The silicone repair agent contains 4% of a sterically hindered phenol heat stabilizer, and the mass ratio of polymethyl methacrylate, poly-N-isopropylacrylamide and the silicone repair agent is: 7:3:16.

[0027] Example 4 This example is applied to a nano-enhanced polyoxymethylene composite plastic particle provided in Example 3, and its preparation method specifically includes the following steps: S1. Add the copolymerized polyoxymethylene matrix and the nano-enhanced phase to a high-speed mixer, premix at 1400 rpm for 7 min, and perform melt plasticization using a twin-screw extruder. The feeding section is at 140 °C, the melting section is at 160 °C, and complete melt plasticization within 30 s at 800 rpm. During the process, add the electromagnetic shielding phase to the melting section of the twin-screw extruder through a side feeding port, and then pelletize the extrudate to obtain semi-finished composite particles; S2. When the semi-finished composite particles are cooled to 55 °C, spray the self-healing phase dispersed in ethanol on the surface of the semi-finished composite particles through an electrostatic spraying device to obtain enhanced composite particles; S3. Place the enhanced composite particles in a plasma treatment device, pass argon at 55 sccm, treat at a power of 300 W for 2 min, then spray an ethanol solution containing 0.4 wt% coupling agent, and dry in an 80 °C environment for 2 h to obtain nano-enhanced polyoxymethylene composite particles.

[0028] Example 5 The difference between this example and Example 1 is as follows: For a nano-enhanced polyoxymethylene composite plastic particle, its raw material components are by mass percentage: copolymerized polyoxymethylene matrix: 82.4%, nano-enhanced phase: 5.4%, electromagnetic shielding phase: 8.1%, self-healing phase: 3.1%, recycling aid: 0.5%, KH-500 coupling agent: 0.5%. Among them, the recycling aid is a nano-benzophenone photo-degradation initiator, and the particle size of the nano-benzophenone photo-degradation initiator is 30 nm.

[0029] The mass ratio of trioxymethylene to dioxolane is: 21:1.

[0030] The length of the carbon nanofibers is 10 μm, the sheet diameter of the boron nitride nanosheets is 500 nm, the specific surface area of graphene is 600 m 2 / g, and the weight ratio of carbon nanofibers, boron nitride nanosheets and graphene is: 1:3:2.

[0031] The diameter of the carbon nanotubes is 10 nm, the particle size of the iron oxide nanoparticles is 5 nm, and the mass ratio of carbon nanotubes to iron oxide nanoparticles is: 5:2.

[0032] The silicone repair agent contains 3% of a sterically hindered phenol heat stabilizer, and the mass ratio of polymethyl methacrylate, poly(N-isopropylacrylamide) and the silicone repair agent is: 8:4:14.

[0033] Example 6 This example is applied to a nano-enhanced polyoxymethylene composite plastic particle provided in Example 5, and its preparation method specifically includes the following steps: S1. Add the copolymerized polyoxymethylene matrix and the nano-reinforcing phase to a high-speed mixer, premix at 1200 rpm for 8 min, and perform melt plasticization using a twin-screw extruder. The feeding section is at 140 °C, the melting section is at 160 °C, and melt plasticization is completed within 30 s at 800 rpm. During the process, add the electromagnetic shielding phase to the melting section of the twin-screw extruder through the side feeding port, and then pelletize the extrudate to obtain semi-finished composite particles; S2. When the semi-finished composite particles are cooled to 50 °C, spray the self-healing phase dispersed in ethanol on the surface of the semi-finished composite particles through an electrostatic spraying device to obtain reinforced composite particles; S3. Place the reinforced composite particles in a plasma treatment device, pass argon at 50 sccm, treat at a power of 300 W for 3 min, then spray an ethanol solution containing 0.3 wt% coupling agent, and dry in an 80 °C environment for 2.5 h to obtain nano-reinforced polyoxymethylene composite particles.

[0034] For the nano-reinforced polyoxymethylene composite particles prepared according to the above Examples 2, 4, and 6, tests are carried out on the tensile strength, electromagnetic shielding effectiveness, heat distortion temperature, 24-h self-healing efficiency, and recovery rate indicators. The test results are shown in Table 1: Index Example 2 Example 4 Example 6 Tensile strength / MPa 136 125 96 Electromagnetic shielding effectiveness / dB 45 54 48 Heat distortion temperature / °C 156 147 136 24h self-healing efficiency / % 83 91 80 Recovery rate / % 92 95 98 Table 1 As can be seen from Table 1, the nano-reinforced polyoxymethylene composite particles prepared in Example 2 have the highest tensile strength and heat distortion temperature and are suitable for environments where high strength is prioritized. The nano-reinforced polyoxymethylene composite particles prepared in Example 4 have relatively balanced functions and are suitable for high-end electronic devices such as 5G base stations. The nano-reinforced polyoxymethylene composite particles prepared in Example 6 have the best recovery rate and are suitable for the electronic field with relatively high environmental protection requirements.

[0035] Simulation Experiment 1 Taking the nano-reinforced polyoxymethylene composite particles prepared in Example 4 as the representative sample and Sekerei X730 plastic as the comparative example, according to the ISO 527 and ASTM D4935 standards, at an environmental temperature of 23 °C, the tensile strength is tested at a tensile rate of 5 mm / min, the electromagnetic shielding effectiveness is tested in the X-band of 8 - 12 GHz, and the 24-h self-healing efficiency is tested at 35 °C. For the representative sample, the recovery rate is measured using the ultraviolet light degradation + magnetic separation method, and for the comparative example, the recovery rate is measured using the 500 °C pyrolysis method. The test results are shown in Table 2: Index Representative sample Control example Tensile strength / MPa 125 110 Electromagnetic shielding effectiveness / dB 54 38 Heat distortion temperature / °C 147 130 24h self-healing efficiency / % 91 None Recovery rate / % 95 45 Table 2 As can be seen from Table 2, compared with the comparative example, the representative sample provided in Example 4 of the present invention has good improvement in the tensile strength, electromagnetic shielding effectiveness, heat distortion temperature, 24-h self-healing efficiency, and recovery rate indicators.

[0036] Simulation Experiment II Taking the nano-enhanced polyoxymethylene composite particles prepared in Example 6 as a representative sample and BASF Ultra Tough Nylon Advanced N as a comparative example, according to the ISO 527 and ASTM D648 standards, at an environmental temperature of 23 °C, the tensile strength was tested at a tensile rate of 5 mm / min, and the electromagnetic shielding effectiveness was tested in the X-band of 8 - 12 GHz. For the representative sample, the recovery rate was measured by the ultraviolet degradation + magnetic separation method, and for the comparative example, the recovery rate was measured by dissolving in dichloromethane. The test results are shown in Table 3: Index Representative sample Control example Tensile strength / MPa 96 80 Electromagnetic shielding effectiveness / dB 48 30 Heat distortion temperature / °C 136 120 Recovery rate / % 98 60 Table 3 As can be seen from Table 3, compared with the comparative example, the representative sample provided in Example 6 of the present invention has a good improvement in terms of tensile strength, electromagnetic shielding effectiveness, heat distortion temperature and recovery rate indicators.

[0037] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A nano-enhanced polyoxymethylene composite plastic particle, characterized in that, Its raw material components by mass percentage include: Copolyoxymethylene matrix: 52.4% - 82.4%; Nano-reinforcing phase: 5.4% - 25.4%; Electromagnetic shielding phase: 8.1% - 11.9%; Self-healing phase: 3.1% - 4.9%; Recycling aid: 0.2% - 0.5%; Coupling agent: 0.2% - 0.5%.

2. The nano-enhanced polyoxymethylene composite plastic particles according to claim 1, wherein, The copolyoxymethylene matrix includes trioxane and dioxolane, and the mass ratio of trioxane to dioxolane is: 19 - 21:1 - 3.

3. The nano-enhanced polyoxymethylene composite plastic particles according to claim 1, wherein The nano-reinforcing phase includes carbon nanofibers, boron nitride nanosheets and graphene, and the weight ratio of carbon nanofibers, boron nitride nanosheets and graphene is: 0.5 - 1:2 - 3:1 - 2; The length of the carbon nanofibers is 5 - 10 μm; The sheet diameter of the boron nitride nanosheets is 100 - 500 nm; The specific surface area of the graphene is 500 - 600 m 2 / g.

4. A nano-enhanced polyoxymethylene composite plastic particle according to claim 1, wherein, The electromagnetic shielding phase includes multi-walled carbon nanotubes and iron oxide nanoparticles, and the mass ratio of carbon nanotubes to iron oxide nanoparticles is: 5 - 8:2 - 4; The diameter of the carbon nanotubes is 10 - 20 nm; The particle size of the iron oxide nanoparticles is 5 - 8 nm.

5. A nano-enhanced polyoxymethylene composite plastic particle according to claim 1, wherein, The self-healing phase includes a silicone repair agent coated with polymethyl methacrylate and poly(N-isopropylacrylamide), and the mass ratio of polymethyl methacrylate, poly(N-isopropylacrylamide) and silicone repair agent is: 6 - 8:2 - 4:14 - 17; The silicone repair agent contains 3% - 5% of sterically hindered phenol heat stabilizer.

6. The nano-enhanced polyoxymethylene composite plastic particles according to claim 1, characterized in that, The recycling aid is a nano-benzophenone photo-degradation initiator, and the particle size of the nano-benzophenone photo-degradation initiator is 10 - 30 nm.

7. The nano-enhanced polyoxymethylene composite plastic particles according to claim 1, characterized in that, The coupling agent is KH-500 coupling agent.

8. A nano-enhanced polyoxymethylene composite plastic particle according to any one of claims 1-7, characterized in that, Its preparation method specifically includes the following steps: S1. Add the copolyoxymethylene matrix and the nano-reinforcing phase to a high-speed mixer, premix at 1200 - 1500 rpm for 5 - 8 min, and use a twin-screw extruder for melt plasticization. During the process, add the electromagnetic shielding phase to the melting section of the twin-screw extruder through a side feeding port, and then pelletize the extrudate to obtain semi-finished composite particles; S2. When the semi-finished composite particles are cooled to 50 - 60 °C, spray the self-healing phase on the surface of the semi-finished composite particles through an electrostatic spraying device to obtain enhanced composite particles; S3. Place the enhanced composite particles in a plasma treatment device, pass argon at 50 - 60 sccm, treat at a power of 300 W for 2 - 3 min, then spray the coupling agent, and dry in an 80 °C environment for 1.5 - 2.5 h to obtain nano-enhanced polyoxymethylene composite particles.